Contact State Estimation via Pulse Noise Detection in Biological Signal Devices

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Solution Overview

Problem

Existing biological signal measuring devices face challenges in accurately determining electrode contact state with the skin, particularly due to variations in skin conductivity and electrode size, leading to incorrect noise detection and unstable contact conditions.

Innovation Solution

A contact state estimating device that uses a signal switching unit to switch direct current voltage pathways between electrodes and estimates contact state based on output signals during anticipated pulse noise occurrences, allowing for high-accuracy discrimination between contact and non-contact states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If skin conductivity measurement is used to determine contact state, then contact state can be estimated, but measurement accuracy deteriorates due to individual skin conductivity variations and dry skin conditions

Engineering Contradiction:

Improvecontact state estimation accuracyVSAvoidmeasurement reliability under varying skin conditions

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the measurement parameter from skin conductivity to pulse noise characteristics. By detecting pulse noise generated during signal pathway switching, the system obtains contact state information that is independent of skin conductivity variations, thereby resolving the contradiction between measurement precision and reliability under varying skin conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the electrical measurement system (conductivity measurement) with a noise detection system. Instead of measuring the electrical property of skin conductivity, the system detects acoustic/electrical noise characteristics during switching operations, which provides contact state information without being affected by skin conductivity variations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If skin conductivity measurement is used to determine contact state, then contact state can be estimated, but accuracy deteriorates due to electrode size variations

Engineering Contradiction:

Improvecontact state estimation accuracyVSAvoidadaptability to different electrode sizes

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the measurement parameter from skin conductivity to pulse noise characteristics. By detecting pulse noise generated during signal pathway switching, the system obtains contact state information that is independent of both skin conductivity variations and electrode size variations, thereby resolving the contradiction between measurement precision and adaptability to different electrode sizes.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If conventional contact state estimation is used, then device operation can be controlled, but false noise detection occurs leading to incorrect contact state determination

Engineering Contradiction:

Improvedevice control based on contact stateVSAvoidcontact state determination accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces pulse noise as an intermediary indicator for contact state determination. Rather than directly measuring skin conductivity or using threshold-based methods, the system uses pulse noise characteristics generated during switching as an intermediary signal that reliably indicates contact state without the drawbacks of direct conductivity measurement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate discrimination between contact and non-contact states, reducing the impact of skin dryness and electrode size variations, and improves contact stability assessment, thereby enhancing the reliability of biological signal measurements.

Implementation Method 1

a first pathway through which the direct current voltage supply unit supplies direct current voltage to the first electrode and an output signal from the second electrode is output and a second pathway through which the direct current voltage supply unit supplies direct current voltage to the second electrode

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentUS11191487B2Contact state estimating device, and biological signal measuring device

Publication Date: 2021.12.07 ASAHI KASEI KOGYO KABUSHIKI KAISHA

AI summary

A contact state estimating device includes: a first and a second electrode brought into contact with an object to be measured; a direct current voltage supply unit; a signal switching unit configured to switch a first pathway through which the direct current voltage supply unit supplies direct current voltage to the first electrode and an output signal from the second electrode is output and a second pathway through which the direct current voltage supply unit supplies direct current voltage to the second electrode and an output signal from the first electrode is output to each other; and a contact state estimating unit configured to estimate a contact state of the first electrode or the second electrode with the object, based on the output signal acquired at a timing at which a pulse noise is anticipated to occur in association with switching between the first pathway and the second pathway.